Edexcel Jun 2015 (IAL) Paper 2 Q22

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22 This is a question about environmental chemistry. (a) Ozone, O3, is a non-linear molecule present in the Earths upper atmosphere. It absorbs ultraviolet radiation from the Sun and so protects living organisms from this type of radiation. (i) Complete the dot and cross diagram for the ozone molecule. Show the outer electrons only. Use dots () for the electrons of the left-hand oxygen atom, crosses (x) for the central oxygen atom and triangles ( ) for the right-hand oxygen atom. (ii) Explain why ozone is a non-linear molecule. (2) (1)(iii) State one harmful consequence to a person of increased exposure to ultraviolet radiation. (1)(iv) What property of ultraviolet radiation makes it more harmful than infrared radiation to living organisms? Justify your answer. (1)14 *P44882A01424*<br /> (v) Nitrogen oxides in aircraft emissions are involved in the depletion of the ozone layer. One of these oxides is the free radical nitrogen monoxide. Define the term free radical. (1)(vi) Complete the equations below for the reaction of the nitrogen monoxide with ozone. Reaction 1 Reaction 2 NO. + O3 (cid:111)++ O3 (cid:111)+Overall Reaction (cid:111) (vii) Based on your answer in (a)(vi), what is the role of the nitrogen monoxide in the depletion of the ozone layer? (3) (1)(viii) Suggest why the release of free radical nitrogen oxides by vehicles, such as buses and lorries, does not affect the ozone layer. (1)(b) Environmentalists are concerned by the increase in concentration in the atmosphere of gases that absorb infrared radiation because of the effect on climate change. (i) Carbon dioxide is a molecule in the atmosphere that absorbs infrared radiation. Explain why this molecule absorbs infrared radiation and what effect this absorption has on the molecule. (2)*P44882A01524* 15 Turn over<br /> (ii) Suggest a gas, of which there is a significant concentration in the atmosphere, which does not absorb infrared radiation. (1)(iii) CFCs make a significant contribution to global warming, despite being present in only very small concentrations in the atmosphere. Suggest a reason for this. (1)(iv) Suggest why there is now little concern over the contribution of CFCs to global warming compared with that of carbon dioxide. (1)(v) Water vapour is another molecule in the atmosphere that absorbs infrared radiation, but it is not considered to be responsible for anthropogenic climate change. Justify this statement. (2)(vi) The term 'carbon neutrality' has become widely used with reference to biofuels. Use of biofuels is one of the measures employed in an attempt to stabilise the level of carbon dioxide in the atmosphere and hence to reduce climate change. Explain the term 'carbon neutrality' and suggest why biofuels are unlikely to be completely carbon neutral. (2)16 *P44882A01624*<br /> (vii) Suggest two measures, other than the use of biofuels, by which the chemical industry could reduce its carbon footprint. (2) 12(Total for Question 22 = 22 marks) TOTAL FOR SECTION B = 39 MARKS *P44882A01724* 17 Turn over<br />

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